Prevalence of tet(X4) in Escherichia coli From Duck Farms in Southeast China

Abstract

ObjectivesCarbapenems, colistin, and tigecycline are critically important antibiotics in clinics. After the global appearance of blaNDM and mcr mediating the resistance to carbapenems and colistin, respectively, tigecycline becomes the last-resort drug against severe human infections caused by multidrug-resistant bacteria. Recently, a mobile tigecycline resistance gene tet(X4) has been identified in Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii that causes high resistance to tigecycline and other tetracyclines. In this study, the prevalence of tet(X4) in E. coli isolates from duck and goose farms in Southeast China was identified and characterized.MethodsFeces, soil, sewage, and dust samples were collected from duck and goose farms along with the southeast coast provinces of China. Antimicrobial susceptibility testing and polymerase chain reaction screening were performed to investigate the phenotype and genotype of tigecycline resistance. Conjugation, S1 pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing were used to determine the transferability, genetic location, and the genomic characteristics of tet(X4).ResultsIn total, 1,716 samples were collected, and 16 isolates (0.9%) recovered from Guangdong, Shandong, and Jiangsu were positive for tet(X4) gene with tigecycline minimum inhibitory concentrations ≥16 mg/L. Notably, among these tet(X4)-positive E. coil isolates, seven of them were from the environment samples (soil and sewage). PFGE and multilocus sequence typing demonstrated that ST3997 was the most prevalent sequence type (eight isolates, 50%) in Jiangsu province. By conjugation assays, 11 isolates were able to transfer tet(X4) plasmid to E. coli C600 recipient, and these plasmids belonged to IncHI1 and IncX1 detected by sequence analysis. tet(X4) was found adjacent to an insertion sequence ISCR2 downstream and a catD gene upstream for all isolates. In addition, multiple-drug resistance to tigecycline, chlortetracycline, ampicillin, florfenicol, ciprofloxacin, gentamicin, trimethoprim/sulfamethoxazole, and fosfomycin was profiled in most of the tet(X4)-positive isolates.ConclusionThe identification of tet(X4) harboring E. coli strains in duck farms and their surrounding environment enlarges our knowledge of the variety and prevalence of tigecycline resistance. The prevalence of tet(X4) raises concern for the use of tetracyclines in animal farming, and the tet(X4) gene should be listed as primary gene for resistance surveillance.

Histone-Like Nucleoid Structuring Protein Modulates the Fitness of tet(X4)-Bearing IncX1 Plasmids in Gram-Negative Bacteria

“…Interestingly, we found that the carriage of tet (X4)-positive plasmids encoding H-NS had low fitness cost in E. coli TOP10 and K. pneumoniae ATCC700603, rather than in S. Enteritidis ATCC13076. These findings support the fact that tet (X4) was reported in E. coli and K. pneumoniae , but not in S. Enteritidis ( He et al, 2019 ; Yu et al, 2021 ), suggesting that the tet (X4)-carrying plasmids impose a high cost in Salmonella . It would be interesting to investigate the underlying mechanisms behind this phenomenon.…”

Mobile Tigecycline Resistance: An Emerging Health Catastrophe Requiring Urgent One Health Global Intervention

“…Ecological niches in which plasmid-encoded TIG resistance tet (X) genes have been detected are shown in Table 1 . Clearly, there is increasing evidence of plasmid-encoded TIG resistance tet (X) genes reported in countries across Europe, Asia, United States, South America, and Africa involving humans, food animals, including chickens, pigs, ducks, pigeons, geese, and cattle, as well as companion animals, food animal products (meats), aquaculture and environment such as soil, livestock-farm water, wastewaters, sewages, and wildlife as reservoirs of MTR ( Bai et al, 2019 ; Chen et al, 2019a , b , 2020 , 2021 ; He et al, 2019 ; Sun C. et al, 2019 , 2020 ; Sun J. et al, 2019 ; Cao et al, 2020 ; Cui et al, 2020 , 2021b ; Ding et al, 2020 ; Du et al, 2020 ; He T. et al, 2020 ; Li et al, 2020 , 2021f ; Ma et al, 2020 ; Pan et al, 2020 ; Ruan et al, 2020 ; Song et al, 2020 ; Wang et al, 2020a , b ; Zhang et al, 2020b , 2021 ; Zheng et al, 2020 ; Cheng et al, 2021a , b ; Feng et al, 2021 ; Hirabayashi et al, 2021a , b ; Hsieh et al, 2021 ; Li et al, 2021e , f ; Lu et al, 2021 ; Marathe et al, 2021 ; Martelli et al, 2021 ; Mohsin et al, 2021 ; Soliman et al, 2021 ; Sun et al, 2021a , b ; Tang et al, 2021 ; Wang et al, 2021f , g ; Xu et al, 2021 ; Yu Y. et al, 2021 ; Wu et al, 2022 ; Zhai et al, 2022 ). We further demonstrate this, through the specific reservoirs in which plasmid-borne transmissible tet (X) and tmexCD-toprJ genes have been detected as shown in Table 2 .…”

“…Moreover, this situation can be exacerbated when an incriminated organism possesses an MTR mechanism [plasmid-encoded tet (X) or efflux pump] and gene coding resistance to other last-resort antimicrobials such as COL (conferred by mcr ), fluoroquinolones, extended-spectrum cephalosporins and fosfomycin. Regrettably, such superbugs have already been isolated from humans ( He et al, 2019 ; Ding et al, 2020 ; Ruan et al, 2020 ; Li et al, 2021a ), food animals ( He et al, 2019 ; Sun C. et al, 2019 ; He T. et al, 2020 ; Li et al, 2020 , 2021c ; Xu et al, 2021 , 2022 ; Yu Y. et al, 2021 ), meat ( Bai et al, 2019 ; Du et al, 2020 ; Mohsin et al, 2021 ; Soliman et al, 2021 ), and environment ( Chen et al, 2019a ; Cui et al, 2020 ; Mohsin et al, 2021 ; Yu Y. et al, 2021 ). Sadly, tet (X) even with genes coding resistance to other last-resort antibiotics, are horizontally/laterally transferred/acquired at a high frequency rate intra/inter-species/genus ( Chen et al, 2019a ; Sun C. et al, 2019 ; Cui et al, 2020 ; Ding et al, 2020 ; Du et al, 2020 ; Marathe et al, 2021 ; Soliman et al, 2021 ; Zhang et al, 2021 ).…”

“…Since healthy and sick human fecal and clinical samples yielded tet (X3/4)-positive E . coli and Acinetobacter and tmexCD1-toprJ1 -positive Klebsiella ( He et al, 2019 ; Wang et al, 2019 ; Ding et al, 2020 ; Zeng et al, 2021 ), and these organisms were also recovered from human sewage ( Cui et al, 2020 ), wastewaters ( Marathe et al, 2021 ), animal feces ( Sun C. et al, 2019 ; Cui et al, 2020 ; Li et al, 2020 ; Yu Y. et al, 2021 ) and slaughterhouse wastewaters/sewage ( Mohsin et al, 2021 ), TIG-r organism/MTR can enter environmental ecosystem through anthropogenic (domestic, laboratory, and hospital) and agricultural (farm and slaughterhouse) sewages and wastewaters ( Table 2 ). Asides improper disposal of wastes into environmental surface waters, rainfall run-offs could carry TIG-r organisms from wastes/sewages/sewage-spills on land/landfills into these surface waters.…”

“…For example, tet (X3/4)-harboring organisms ( E . coli and Acinetobacter ) and high abundance of these genes as well as tmexCD1-toprJ1 , have been detected in farm soil and soil within livestock farms ( Sun J. et al, 2019 ; Cao et al, 2020 ; Li et al, 2020 ; Cui et al, 2021b ; Yu Y. et al, 2021 ). Garbage/synathropic flies that feed/breed on animal manure can pick these organisms from the soil and transport them to other ecological niches.…”